1. Technical Field
This invention relates generally to an apparatus and process for reclaiming paper mill sludge and to useful products derived therefrom, and, more specifically, to a safe, energy efficient, fully integrated system for recycling paper mill sludge to obtain a wide variety of ecologically safe products.
2. Background
It is well known that waste cellulosic fiber and paper mill sludge, which are produced in large quantities in most industrial nations of the world today due to the large usage of paper, constitute one of our most serious environmental problems. Paper mill sludge has substantially little usage as a material that can be employed in other industrial applications. Because of its non-utility, the paper mill sludge is merely discarded, along with other waste cellulosic fiber. This creates a tremendous disposal problem as paper mill sludge contains many environmental contaminants.
In U.S. Pat. No. 5,505,774 this inventor disclosed a continuous flow process for treating paper mill sludge utilizing calcium oxide and silica. In this process calcium oxide and silica were simultaneously and continuously discharged along with a paper mill sludge slurry into a primary blender, where the components were blended.
This inventor also has utilized calcium oxide and silica in methods of treating waste cellulosic fibrous material to obtain useful products such as animal waste absorbent materials, soil supplements and floor dry materials.
In U.S. Pat. No. 5,372,314 a method of manufacturing animal bedding material is disclosed. In this process waste cellulosic fibrous material is finely shredded after which any metal component is removed. The shredded fibrous material is then mixed with calcium oxide and water until a temperature of about 120-140.degree. F. is achieved. This mixture is then neutralized with silica diatomite plankton or non-swelling clay to obtain a final mixture. The end product is especially useful as cat litter.
The process of U.S. Pat. No. 5,456,737, a continuation-in-part of the '314 patent, involves shredding and demetalling waste cellulosic fibrous material and then thoroughly mixing the fibrous material with an agricultural wetting agent and a milk of lime. Similar to the '314 process, this mixture is then neutralized with silica diatomite plankton or non-swelling clay to obtain a final mixture.
U.S. Pat. No. 5,510,310, also a continuation-in-part of the '314 patent, relates to a method for manufacturing a floor dry material from shredded and demetalled fibrous material. The fibrous material is mixed with a biodegradable surfactant, calcium oxide and water, after which a citric based solvent degreaser and silica diatomite plankton or non-swelling clay are added.
U.S. Pat. Nos. 5,372,314; 5,456,737; 5,505,774 and 5,510,310 are incorporated herein by reference.
While the above referenced methods of reclaiming or recycling paper mill sludge and waste cellulosic fibrous material provide safe and useful end products, there exists a need for an integrated process from which a single source of paper mill sludge can be utilized in an economical, safe (explosion resistant) continuous flow procedure to output environmentally acceptable products for different end-use applications. This need has not been fulfilled by others who have utilized paper mill sludge or waste cellulosic fibrous materials to form agglomerated cellulosic particles.
In particular, U.S. Pat. No. 4,799,961 to Friberg discloses the use of pulped paper or waste material from paper mills as part of a process for forming cementitious fiber impregnated construction compositions. But the Friberg process has certain limitations that make its commercial application of questionable feasibility.
U.S. Pat. No. 4,621,011 discloses a cellulosic particle manufactured by agglomerating a fibrous cellulosic feed material in the presence of water, compacting the surface of the agglomerated particles, and drying the particles.
U.S. Pat. No. 5,019,564 provides an agricultural granule for carrying and releasing an incorporated biocidal or nutritional agricultural chemical. The granule is formed by the agitative agglomeration of a plant fiber slurry, such as primary de-inked paper sludge.
U.S. Pat. Nos. 4,621,011, 4,799,961 and 5,019,564 are incorporated herein by reference. None of these patents, however, provides an integrated process for reclaiming paper mill sludge and none addresses the treatment of paper mill sludge or waste cellulosic materials to ensure that the resulting end product is substantially free of environmentally deleterious materials.
Thus, the object of the present invention is to provide such an integrated system for reclaiming paper mill sludge and waste cellulosic fibrous material such that a variety of useful, environmentally safe products can be manufactured in a continuous flow procedure.
It is a further object of the present invention that the continuous flow procedure be safe to operate and explosion resistant.